This invention relates to a device for destroying insects. More particularly, the invention relates to an insect bait station whereby granules containing poison may be administered to insects and whereby insects will remove poison containing material from the station and carry the material back to the insect habitat for feeding of other insects thereby killing other insects. This is done with a spill resistant station configuration minimizing the risk to children or domestic animals. The station of this invention has means for guiding said insects to the poison containing bait.
Various types of devices have been known in the prior art for destroying insects. In some devices, the insects are trapped in the device after entering, either by mechanical construction, or by sticking to a gummy substance. In either instance, such prior art device is soon full and useless. In devices which contain a poison, the devices were not appropriate for granules because either it was easy to shake out loose poison, or probe through openings to reach the poison, thus making them a danger to children or small domestic animals. In addition, prior devices are generally of a construction that the interior of the device is difficult to view so that it is not readily ascertainable whether insects are using the device or how much poison has been used.
U.S. Pat. No. 4,173,093 relates to a catching device for cockroaches. This device is a trap as opposed to the bait station of the present invention. The insect moves across the supporting surface beneath the device and between the lower surface of the floor portion of the device. This permits the cockroach to enter the central axial opening into the device housing. The cockroach is lead through a passage way into the central portion of the device trapping the insect.
U.S. Pat. No. 4,263,740 relates to a crawling insect trap wherein the device is designed so that either upon exiting or entering the center opening of the annular flange to retrieve food the insect will fall back into the trap.
Other bait stations in the prior art are of the type wherein a series of guides and baffle means guide the crawling insect through openings in the periphery of the station to the central point area, for example, U.S. Pat. No. 4,563,836 and U.S. Pat. No. 4,837,969. Such stations must contain bait which is not granular. The bait therein is preferably of a paste-like or solid "cookie" consistency.
It is therefore an object of this invention to provide an insect bait station suitable for granular baits, which is attractive to the feeding insect and has external means for guiding the insect to the bait.
It is therefore an object of this invention to provide an insect bait station which is substantially spill resistant and attractive to the feeding insect.
A further object is to provide an insect feeding station which minimizes risk to children or pets.
A further object is to provide an insect feeding station in which it is readily possible to detect the use of the poison bait.
Another object is to provide an insect bait station with means for guiding insects toward the poison-containing bait and to allow insects to carry said bait away from the station back to the insects' nest.
These and other objects of the invention will become apparent as the description thereon proceeds. The objects of this invention may be attained and the disadvantages of the prior art trapping devices are overcome by the use of the present invention. The device of the present invention has a base portion for holding a poison bait and a cover therefor. The bait station comprises a base with a tunnel entrance having an opening at each end, a center mound therein cooperating with said tunnel entrance, with an internal opening as an entry port or access port, for insect access to the bait inside the base. In the preferred embodiment the bait station has a continuous cover with a central depression cooperating with and in close proximity to the internal opening in the center mound, to restrict the spillage of granules out of the station. The base may be of any configuration, e.g., round, oval, square, rectangular, or hexagonal and the like; however, it is necessary for the corresponding cover to contain a depression to cooperate with the internal opening to deflect granules away from the entry port if the station is tilted or shaken.
The poison is preferably formulated in a composition of the type known as bait, i.e., it is a mixture of poison in admixture with a food material attractive to the target insects, such as, but not limited to, flour, molasses, peanut butter, citrus pulp, animal fats such as lard and tallow, with an organic filler such as bran, and crushed puffed grain, pregel defatted corn cob grits or a starch matrix are also useful. The bait is preferably granular or paste-like. Other additives can be added to the formulation of the bait, for example, dry pupa of silkworm, various animal digestive parts, such as freeze dried poultry liver, and the like.
It is preferable to formulate ant baits with a matrix material. The ideal matrix material for the bait for use in the instant bait station would be one that can be picked up by the foraging insect and carried back to the nest to be passed around to other insects. Contact insecticides would not generally be suitable, unless a slow-acting contact poison were used, since the bait material as used in this invention would best be useful for killing foragers and for bringing poison to a colony. Sulfimide, hydramethylnon, and avermectin are examples of suitable insecticides. Preferably, the insecticide constitutes 0.2-10% by weight of the bait.
The instant bait station is particularly useful for supplying bait to insects. The insect baits of this invention are especially effective for the control of ants, such as, but not limited to, the southern fire ant Solenopsis xyloni!, leaf cutting ants Acromyrmex versicolor!, Argentine ants Iridomyrmex humilis!, cornfield ants Lasius alienus!, pavement ants Tetramorium caespitum!, larger yellow ants Acanothomyops interjectus!, thief ants Solenopsis molesta!, and the red and black imported fire ants Solenopsis invicta! and Solenopsis saevissma richteri!, respectively. These ants are serious economic pests which have been known to harm human beings, livestock, and agronomic crops. Therefore, it is highly desirable to control them. Other ants that can be controlled are nuisance pests such as Pharaoh ants Monomorium pharaohnis!, odorous house ants Tapinoma sessile!, and acrobat ants Crematogaster cerasi!.
The base may be formed as a unitary piece from a deformable material, such as a plastic, by known methods. One method for forming the base is from a flat sheet of plastic which is either thermoformed or vacuum formed over a suitably designed mold to form a bridged tunnel within the base which acts as a receiving area for the bait. It is also possible to form the base by injection molding of a molten plastic into a suitably designed mold. The cover of the device is also formed in like manner as a unitary piece which is attached to the top of the device to prevent access by children via the cover. The cover is preferably permanently affixed to the top of the device. The cover is permanently affixed to the base and, optionally may have at least a part which is transparent so that the poison bait is visible through the cover.
The insect bait station of the present invention can be made of paper, wax, plastic, or metal, provided the sloping inclines and declines are of a material which will allow the insect, particularly ants, to efficiently walk thereupon to access the poison containing bait in the interior of the station and to exit the station and return to the nest. Although any of the enumerated materials will suffice, moldable plastic, such as polystyrene, would be preferred.
In one embodiment of the present invention, the cover which is affixed to the base has at least a section thereof which is transparent, so that the poison is visible therethrough. Alternatively, the entire cover may be transparent. In this latter embodiment, it may be desirable to color the floor of the compartment with a contrasting color before filling the bait station, and more desirably the contrasting color may be luminous so that it is readily visible in darkened areas. As bait is removed by insects, the contrasting color underneath becomes visible and provides an indication whether insects are using the station and how much bait has been used.
In an alternative embodiment of the present invention, the insect access port in the base remains closed and sealed until a user opens the access port, such as by punching a perforated hole or removing a cover. This embodiment prevents spillage or degradation of bait prior to use for insect feeding.